The use of herbicides to control weeds in turf is well known. There are two types of herbicide applications, pre-emergence herbicides prevent weed seeds from germinating or emerging and post-emergence herbicides that kill emerged and actively growing plants.
Pre-emergence turf herbicides are generally more effective, but must be applied early in the season before annual weed seeds germinate. In order to provide season-long control most pre-emergent herbicides need to be reapplied six to eight weeks after the initial application.
Post-emergence turf herbicides are used to control weeds after germination and emergence from the soil. The benefit of using a post-emergence turf herbicide for weed control is that it is used only where an infestation is present.
It would be most beneficial to provide a pre- and post-emergence turf herbicide that provides synergistic control of weeds such as chickweed, clover, cudweed, parsley, dock, plantain, medic, dandelion, sorrel and crabgrass in one application without injury to turf grasses.